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Blocks are injections of medication onto or near nerves.
The medications that are injected include local anesthetics,
steroids, and opioids. In some cases of severe pain it
is even necessary to destroy a nerve with injections of
phenol, pure ethanol, or by using needles that freeze
or heat the nerves. Injections into joints are also referred
to as blocks. Although not technically correct, such “shorthand”
is commonly used.
Why
do we do blocks?
1.Blocks with local anesthetic can be used to control
acute pain. (Hence, the shot at the dentist or the epidural
block for a surgery or a delivery.)
2.Pain and injury often makes nerves more sensitive, so
that they signal pain with less provocation. Think about
lightly brushing against your skin when you have a sunburn.
Blocks can provide periods of dramatic pain relief, which
promotes the desensitization of sensory pathways.
3.Steroids
can help reduce nerve and joint inflammation and can reduce
the abnormal triggering of signals from injured nerves.
4.Blocks
often provide diagnostic information, helping to determine
the source of the pain.
Remember,
blocks are not the best treatment for all pain problems.
Patients often ask me, “Doc, can’t you just do a nerve
block?” Often blocks are not possible, are too dangerous,
or simply are not the best treatment for the problem.
Spinal
Injections:
The most common spinal injection is the lumbar epidural
steroid injection. This is particularly useful for pain
that radiates from the lower back into a leg, and is caused
by disc herniation or spinal stenosis (narrowing around
the nerves) which triggers nerve root irritation. Similar
injections can be very useful in the cervical spine, where
the symptoms will extend into the arms. Thoracic epidural
steroid injections are most commonly used to reduce the
pain associated with herpes zoster (shingles). Such blocks
may reduce the risk of developing persistent postherpetic
neuralgia (i.e., pain which persists long after the skin
eruption has healed).
The
facet joints of the spine can also cause pain. Injections
into the facet joints or blocks of the nerves that go
to the facets can often be very helpful with these pains.
This problem is more common in the lumbar spine, but also
occurs in the neck.
Discograms
(intradiscal injections of contrast under fluoroscopy
or CT imaging) can determine if and which disc is the
source of the pain. This can help a surgeon determine
which levels of the spine require surgery. If the patient
is found to have a painful disc, they may be a candidate
for a new and promising technique, intradiscal electrothermoplasty
(IDET). In a procedure similar to a discogram, a wire
is temporarily inserted into the disc and used to heat
the disc. This destroys the invading sensory nerves and
causes the proteins of the disc wall to reshape and slowly
strengthen (over 3-6 months). The procedure cannot be
done if the disc has already severely degenerated.
Copyright
© 2000, Steven Richeimer, MD.
You may reach The Richeimer Pain Institute at www.helpforpain.com
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